Process for the preparation of polyhalobenzylic disulfooxonium compounds

ABSTRACT

Polyhalobenzylic disulfooxonium compounds are produced by the reaction of aromatic methyl, halomethyl or hydroxymethyl substituents with sulfur trioxide. The disulfooxonium salts are readily converted to alcohols by hydrolysis to provide monomers for the production of fire resistant polymers and additives for polymers. Likewise, the disulfooxonium compounds of this invention present chemical intermediates for a wide range of useful products such as halogenated pesticides.

CROSS-REFERENCE TO RELATED APPLICATION

This is a division, of application Ser. No. 607,326, filed Aug. 25, 1975now U.S. Pat. No. 4,075,238, which is a continuation of Ser. No.410,723, filed Oct. 29, 1973, now abandoned which is acontinuation-in-part of Ser. No. 123,014, filed Mar. 10, 1971, nowabandoned.

THE INVENTION

Although sulfur trioxide is recognized as a strong oxidant, it has notbeen used extensively due to its random reaction pattern withhydrocarbons. With paraffins and olefins, the reaction product withsulfur trioxide is a messy, intractable, dark mixture of oxidation,condensation, polymerization, sulfonation and sulfation products,demonstrating the uncontrollability of the reaction. In contrast, as anaromatic sulfonating agent and as a sulfating agent for alcohols, sulfurtrioxide is used extensively, these reactions being well developed anddocumented.

The process of the instant invention illustrates the novel use of sulfurtrioxide in oxidation and insertion reactions in the absence ofuncontrollable competing reactions to afford a novel class of oxoniuminner salts, the disulfooxonium type inner salts, which are completelystable but highly reactive compounds.

This invention comprises a novel class of halogenated organic compoundsand methods for their preparation, said class of compounds being usefulfor the preparation of a variety of halogenated products, which in turnare useful as monomer precursors for polymeric systems, as additives forpolymers, especially to provide fire resistance, as pesticides and aschemical intermediates. Typically, the compounds of this invention maybe used to form the compounds and analogs thereof disclosed in JapanesePat. No. 16,457; U.S. Pat. Nos. 2,621,168; 2,608,592; 2,564,214 and2,815,301; British Pat. No. 977,961; German Patent 1,105,862; Journal ofAmerican Chemical Society, Vol. 71, 2756 (1949); Journal of AmericanChemical Society, Vol. 69, 1914 (1947); Chemical Weekblad, Vol. 9, 862(1912) and Industrial Engineering Chem. Prod. Res. and Dev., Vol 4, 259(1965).

More particularly, this invention relates to the novel class of organiccompounds properly referred to as polyhalobenzylic disulfooxoniumcompounds represented by the generic formula (A): ##STR1## WHEREIN

Ar is an aromatic nucleus

Hal is a halogen selected from the group consisting of fluorine,chlorine, bromine and iodine;

Y is a substituent selected from the group consisting of fluorine,chlorine, bromine and hydroxyl, provided when X is ##STR2## at least oneY is hydroxy;

X is a substituent selected from the group consisting of hydrogen and##STR3## wherein Y is the same as defined above;

m, n and p are integers so selected that their sum is the number ofsubstitutable positions available on the aromatic ring, which when Ar isbenzene is six; when Ar is naphthalene is eight; when Ar is anthraceneand phenanthrene and pyrene is ten.

The aromatic nucleus Ar is intended for the purposes of this disclosureto embrance the ring structures of benzene, naphthalene, anthracene,phenanthrene and pyrene. Thus, Ar is an aromatic hydrocarbon moiety ofthe benzene series containing from 1 to 4 six membered rings in whicheach substitutable hyrogen on the ring has been replaced by a halogen.

This novel class of compounds is obtainable by the reaction of theappropriate halogenated aromatic compounds with reagents containingsulfur trioxide such as neat sulfur trioxide proper, sulfuric acidsolutions of SO₃ (oleum), sulfur trioxide adducts, such as those withdioxane and amines and chlorosulfonic and fluorosulfonic acids.

The following chemical equations illustrate some of these novelreactions: ##STR4## A very significant aspect of the present inventionis the discovery that the reaction with sulfur trioxide and sulfurtrioxide containing reagents can be carried out with concomitantoxidation of the side chain of the aromatic substrates. The significanceof this finding lies in the fact that even methyl groups on the aromaticnuciei can be readily and quantitatively oxidized and transformed intoproducts represented by generic formula A shown above with Y beinghydroxy in this case. In these reactions one mole of sulfur trioxide permethyl group is used up in the oxidation step proper, yielding one moleof sulfur dioxide, as illustrated by the following reactions: ##STR5##

A further very useful variant of the oxidation reaction is thetransformation of the methyl group into a geminal dioxonium derivativeby an excess of the sulfur trioxide reagent: ##STR6##

It is of considerable synthetic value that the oxidation of the methylor substituted methyl side chains on the aromatic nuclei does not gobeyond the geminal dioxonium stage even when a large excess of sulfurtrioxide is used, a fact that results in subsequent transformations(vide infra) in very pure products.

The wide scope of these novel reactions is indicated by the largevariety of halogenated aromatic compounds which readily undergo thesetransformations and yield a multitude of useful products. Derivatives ofall four of the common halogens are equally suitable as startingmaterials, if they are present in form of mono-, di- or polynucleararomatic compounds. The latter two classes comprise both isolated andfused ring aromatic species, some of which are listed below and in thedetailed examples. All of these halogenated aromatic compounds carry oneor more side chains consisting of methyl, halomethyl or hydroxymethylsubstituents. As representatives of the multitude of substrates suitablefor the preparation of the oxonium compounds covered by this inventionthe following compounds can be listed: Pentafluorotoluene,tetrafluoro-o-xylene, trifluoromesitylene, pentachlorotoluene,pentachlorobenzyl chloride, tetrachloro-m-xylene, trichloropseudocumeneα,α¹,2,3,5,6-hexachloro-p-xylene, pentachlorobenzyl alcohol,heptachloro-1-methyl-naphthalene, heptachloro-2-methylnaphthalene,hexachloro-2,7-dimethyl-naphthalene, octachloro-9,10-dimethylanthracene,octachloro-4,4'-dimethylbiphenyl, pentabromotoluene, pentabromobenzylfluoride, tetrabromo-p-xylene,1,3,5,7-tetrabromo-2,6-dimethylnaphthalene, tribromomesitylene,dibromodurene, pentaiodotoluene, pentaiodobenzyl fluoride,tetraiodo-o-xylene, tetraiodo-m-xylene,α,α'-dichloro-2,3,5,6-tetraiodo-p-xylene, triiodomesitylene,2-chloro-3,4,5,6-tetrabromotoluene, 2-chloro-3,4,5,6-tetraiodotoluene,2-chloro-3,5,6-tribromo-4-iodotoluene,2,5-dibromo-α,α',3,6-tetrachloro-p-xylene. The reactions of many ofthese aromatic compounds are treated in detail in the specific examplesshown later.

As a result of the wide range of reactivities of both the aromaticreactants and the sulfur trioxide containing reagents a rather widerange of the desirable reaction temperatue exists. While formation ofthe oxonium compounds from benzylic alcohols can take place as low as-80° C., reactions involving concomitant oxidations are best carried outabout 0° C., often at the boiling point of liquid SO₃, between 45° and50° C., and with less reactive compounds, up to and in some instancesabout 150° C. The judicious selection of the proper SO₃ containingreagent usually obviates the use of a foreign solvent and often it isadvantageous to use an excess of liquid SO₃ (which is a good solvent) orsulfuric acid (which is a liquid vehicle). A small amount (5-10%) ofconcentrated sulfuric acid, when added to liquid sulfur trioxide, hasoften a beneficial effect in increasing the rate of the oxidation of thearomatic substrate. It has been found, however, that when used in largeamounts as for examaple, in the form of 20% oleum as the reactionmedium, sulfuric acid can drastically alter the course of reaction asexemplified by reaction (13) (vide infra). In a few cases where neededor where beneficial, solvents not affected or not readily attaked by thesulfur trioxide species can be employed. Most often fluorinatedaliphatic halocarbons, such as trichlorofluoroethane,trichlorofluoromethane and 1,1-difluorotetrachloroethane can beemployed. The reactions are carried out usually at atmospheric pressure,followed if desired by the application of vacuum to recover excessliquid sulfur trioxide. When the reaction is accompanied by an oxidationstep provisions should be made for the removal of the gaseous sulfurdioxide coproduct.

The structure of the oxonium compounds represented by generic formula Arests on the following:

(1) Stoichiometry of the reaction. Since most of the reactions describedtake place with quantitative conversion, the weight of the isolatedproduct is indicative of its composition. When accompanied by anoxidation step, the amount of the evolved sulfur dioxide gas indicatesthe extent of oxidation and the number of methyl and substituted methylgroups involved.

(2) Element analysis of the product also confirms the gross composition.Because of its high reactivity and hydroscopic nature, indirectanalyses, e.g. after its decomposition with water and determination ofthe liberated sulfuric acid and carbon, hydrogen and halogen combustionanalyses, are best carried out.

(3) Nuclear magnetic resonance spectroscopy provides the bestconfirmation of the specific structure represented by (A) for instancethe single proton nuclear magnetic resonance peak at 6.3-6.5 parts permillion (ppm) downfield from the reference tetramethylsilane iscompatible only with the following structure: ##STR7##

(4) The numerous reactions of the oxonium compounds, many of which takeplace in quantitative yield, provide also ample proof for thecorrectness of the molecular structure represented by generic formula(A). Representative reactions are illustrated with the pentachlorobenzyloxonium compound: ##STR8##

A variant of these reactions was encountered with haloaromatic compoundswhich carry more than one methyl group. When these reactants wereoxidized with sulfur trioxide and the resultant oxonium compounds weredecomposed by water, the reaction products were the corresponding di- orpolyhydroxymethyl compounds analogous to the products of equation (1)When the oxidation was effected with a sulfur trioxide sulfuric acidmixture (as, for example, with 20% oleum) the reaction products werealdehydes in which one of the methyl groups remained intact. Thisunusual reaction (detailed in Examples 64-67) can be represented byequation (13) using tetrachloro-p-xylene as the specific reactant.##STR9##

For contrast, when sulfur trioxide was used in the absence of sulfuricacid, the reaction followed the course depicted in equation (1a).##STR10##

Even more surprisingly, when the diol itself was exposed to oleum, themethyl-aldehyde was the reaction product. ##STR11##

The products of these novel reactions can thus be categorized by thefollowing generic formulae:

The products of reaction (1) can be represented by (B)

    hal.sub.m Ar(CH.sub.2 OH).sub.n                            (B)

where Ar, Hal, M and n are the same as defined in generic formula (A).

The products of reaction (2) can be represented by (C)

    hal.sub.m Ar(CH.sub.2 OSO.sub.2 OM).sub.n                  (C)

where Ar, Hal, m and n are as defined above and M is a metal comprisingthe alkali, the alkaline earth and other readiy available cationicspecies.

The products of reactions (3), (4) and (5) can be represented by (D).

    hal.sub.m Ar(CH.sub.2 Hal').sub.n                          (D)

where Ar, Hal, m and n are as defined above and Hal' is a halogencomprising chlorine, bromine and iodine.

The products of reaction (6) are represented by (E).

    hal.sub.m Ar(CH.sub.2 Ar).sub.n                            (E)

where Ar, Hal, m and n are as defined above. Although illustrated onlywith benzene, suitable reactants include a wide range of aromaticcompounds which contain at least one hydrogen available for thesubstitution reaction illustrated in (6). Thus suitable aromaticsubstrates include mono-, di- and polyhalobenzenes, such asfluorobenzene, chlorobenzene, o-dichlorobenzene, p-dichlorobromobenzene,1,2,4-trichlorobenzene, bromobenzene, p-chlorobromobenzene, iodobenzene;mono-, di- and polyalkylbenzenes, such as toluene, xylenes, mesitylene,pseudocumene, durene, ethylbenzene, isopropylbenzene, tert-butylbenzene,o-chlorotoluene, dodecylbenzene; isolated and fused di- and polycyclicaromatic compounds, such as biphenyl, naphthalene, anthracene,phenanthrene, pyrene, 1-chloronaphthalene, 9,10-dichloroanthracene,triphenylmethane and indene.

The products of reactions (7) and (8) are shown by (F). ##STR12## whereAr, Hal, m and n are as defined above and R is a hydrocarbon residuecomprising aliphatic, cyclo-aliphatic and aromatic groups which may besubstituted by halogens.

Suitable reactants for reactions (7) and (8) thus include hydrogencyanide, acetonitrile, propionitrile, butyronitrile,trichloracetonitrile, trifluoroacetonitrile, benzonitrile,p-chlorobenzonitrile, acrylonitrile, propiolic acid nitrile, as well asdi- and polynitriles, such as cyanogen, glutaronitrile, adiponitrile,phthalonitrile. When di- or polyfunctional oxonium compounds, such asthose derived from xylene and mesitylene are reacted with difunctionalnitriles, such as malononitrile, succinonitrile, adiponitrile, polymericpolyamides are produced.

The products of reaction (9) are represented by (G): ##STR13## where Ar,Hal, m and n are as defined above. The products of reaction (10) arerepresented by (H):

    hal.sub.m Ar(CH.sub.2 CHClCOOH).sub.n                      (H)

where Ar, Hal, m and n are as defined above

The products of reaction (II) are shown by (I):

    hal.sub.m Ar(CH.sub.2 CCl.sub.2 COOH).sub.n                (I)

where Hal, Ar, m and n are as defined above.

The product of reaction (12) are represented by (J):

    hal.sub.m Ar(CHO).sub.n                                    (J)

where Hal, Ar, m and n are as defined above.

The products of reactions (13) and (14) are represented by (K):

    hal.sub.m Ar(CH.sub.3).sub.p (CHO).sub.q                   (K)

where Ar, Hal, m are as defined above, and p and q are integers with thefollowing relationship: p = q = n, where n is the same as defined above.

These reactions which are characterized by high conversion and by thepurity of the products and which take place in analogous fashion withvarious mono-, di-, and tri-oxonium compounds as well as otherhalogenated aromatic compounds are thus eminently suitable forpreparative (manufacturing) processes. The variety of mono-, di- andpolyfunctional end products of these reactions find uses as additives orpolymers which they render fire resistant by virtue of their highhalogen content, as monomers for the preparation of a variety ofpolymeric systems, as chemical intermediates and as pesticides.

The following examples are given for purposes of illustration of thisinvention and are not to be construed as limiting it except as set forthin the claims.

EXAMPLE 1 Preparation of 2,3,4,5,6-pentachlorobenzyldisulfooxoniumhydroxide inner salt from pentachlorotoluene and sulfur trioxide##STR14##

Liquid sulfur trioxide, (200 ml, 385 g) was added to 26.4 g. (0.1 mole)of pure 2,3,4,5,6-pentachlorotoluene (mp 224°-225° C.) placed in a 500ml 3-neck tared flask provided with stirrer, thermometer and refluxcondenser the end of which was attached to a bubble counter so that therate of gas evolution during the reaction can be visually estimated.External heat was applied to the flask to bring the sulfur trioxide toreflux. Soon a light blue color developed, which turned gradually deeperto a vivid royal blue. The color change was accompanied by gas evolutionwhich was identified as sulfur dioxide. The steady gas evolution, whichbegan after 10 minutes of reflux, lasted for 2-3 hours, after which itbecame gradually slower and the reaction mixture gradually acquired adark green-gray color. The weight of the reaction mixture at this timeindicated a loss of 6.9 g, as compared to the theoretical loss of 6.4 g,corresponding to one mole of sulfur dioxide evolved. The excess ofsulfur trioxide, which acted also as a solvent during the reaction wasdistilled off first at atmospheric pressure, then under aspirator vacuumat a temperature not exceeding 70° C. The weight (45.2 g) of theproduct, a greenish-grey solid, indicated as C₇ H₃ Cl₅ O₇ S₂ compositionand this was confirmed by its hydrolysis which yielded 0.2 moles ofsulfuric acid and 0.1 mole of pentachlorobenzyl alcohol, identified byelemental analysis, infrared spectroscopy, melting point and nuclearmagnetic resonance spectroscopy (see Example 23). The evolvement of thereaction was also followed by nuclear magnetic resonance (nmr)spectroscopy which indicated that even in the early stages of thereaction the characteristic proton resonance of pentachlorotoluene at2.52 ppm downfield from tetramethylsilane (TMS) completely disappeared.Instead, a new peak at 4.55 ppm appeared, which is assignable to theradical cation formed from pentachlorotoluene by the loss of oneelectron. During the refluxing and sulfur dioxide eveolution period twoadditional peaks developed in increasing intensities and inapproximately in a 2:1 ratio at 6.29 and 9.21-9.60 ppm (the later issomewhat variable during the reaction). The former corresponds to thetwo benzylic hydrogens adjacent to the oxonium moiety and the lattercorresponds to the acidic proton of the sulfuric acid moiety. Theintensity of the peak corresponding to the radical cation, whichaccounts for the intense blue color, diminishes to a few percent after 2hours of reflux and the intensities of the protons of oxonium compoundbecome constant after this period.

EXAMPLE 2 Preparation of pentachlorobenzyldisulfooxonium hydroxide innersalt from pentachlorobenzyl alcohol and sulfur trioxide ##STR15##

The procedure of Example 1 was repeated, except that the equivalentamount (28.0 g) of pentachlorobenzyl alcohol,mp 195°-196° C. wassubstituted for pentachlorotoluene. In contrast to the former case onlya transient blue color appeared which on reflux turned greyish green,but there was no gas evolution. The identity of the product was that ofthe former example was established by nuclear magnetic resonance, whichshowed the two peaks of the oxonium compound.

EXAMPLE 3 Preparation of pentachlorobenzyl(chlorosulfonyl)sulfooxoniumhydroxide inner salt for pentachlorobenzyl chloride and sulfur trioxide##STR16##

The procedure of Example 1 was repeated, except that the equivalentamount (29.9 g) of pentachlorobenzyl chloride, mp 100°-101° C., wassubstituted for pentachlorotoluene. A 10 minute refluxing periodsufficed to convert the halide into the halooxonium compound, withoutgas evolution and without the occurrence of a highly colored solution.For subsequent reaction of this product see Examples 49 and 58. Thechemical shift of this oxonium compound was at 6.35 ppm in SO₃ solution.

EXAMPLE 4 Preparation of the nomooxonium compound from pentabromotolueneand sulfur trioxide ##STR17##

When the procedure of Example 1 was repeated with the substitution of48.7 g 2,3,4,5,6-pentabromotoluene (mp 284°-286° C.) forpentachlorotoluene, gas evolution and the development of a dark greencolor accompanied the formation of the oxonium compound which wasobtained in quantitative yield.

EXAMPLE 5 Preparation of the monooxonium compound frompentafluorotoluene and sulfur trioxide ##STR18##

The procedure of Example 1 was repeated except that 18.2 g of2,3,4,5,6-pentafluorotoluene bp 117°-118° C., n_(D) ²⁰ 1.4023, wassubstituted for pentachlorotoluene and that the refluxing period wasextended to six hours. The originally colorless solution after 3 hoursturned deep red and the methyl protons at 2.44 ppm disappeared, givingrise to the methylene protons at 6.05 ppm and the acid proton at 9.58ppm. The oxonium compound was hydrolyzed to the benzylic alcohol asdescribed in Example 68.

EXAMPLE 6 Preparation of pentachlorobenzalbis(disulfooxonium)dihydroxidebis(inner salt) from pentachlorotoluene and sulfur trioxide ##STR19##

The procedure of Example 1 was repeated, except that the refluxingperiod of sulfur trioxide was extended to 24 hours. At the end of thisperiod the reaction product weighed 398.2 g, thus indicating a weightloss of 13.2 g, corresponding to the evolution of 0.2 moles of sulfurdioxide. Distillation of the excess of sulfur trioxide resulted in therecovery of 313 g. of material, or 93% of the theory. Stripping of thereaction mixture under the vacuum of a water aspirator resulted in afurther weight loss of 22 g., and the isolation of 61.1 g. of thedioxonium compound, which represents an essentially quantitative yield.

The identification of the dioxonium compound was done by nuclearmagnetic resonance which showed two peaks at 8.9 and at 10.15 ppm, andby the quantitative analysis of its hydrolysis products, which includedfour mole equivalents of sulfuric acid and one mole equivalent ofpentachlorobenzaldehyde (see Example 33). The formation of sulfurdioxide and of the solid product in quantitative yields is ompatibleonly with the stoichiometry indicated above.

EXAMPLE 7 Preparation of the dioxonium compound from pentabromotolueneand sulfur trioxide ##STR20##

The procedure of Example 6 was repeated, except that 48.7 g. of2,3,4,5,6-pentabromotoluene (mp. 284°-286° C.) was substituted forpentachlorotoluene. The dioxonium compound was identified by theelemental analysis of its hydrolysis products, which included four molesof sulfuric acid and one mole of pentabromobenzaldehyde (see Example35), as well as by its formation in quantitative yield by thestoichiometry shown above.

EXAMPLE 8 Preparation of pentachlorobenzal (chlorosulfonyl)sulfooxoniumhydroxide (disulfooxonium hydroxide)bis(inner salt) frompentachlorobenzyl chloride and sulfur trioxide ##STR21##

The procedure of Example 3 was repeated, except that the heating periodwas extended to 24 hours. Stripping of the excess of sulfur trioxide andhydrolysis of the dioxonium compound resulted in the formation of fourmoles of sulfuric acid, one mole of hydrochloric acid and one mole ofpentachlorobenzaldehyde, mp. 201°-203° C.

EXAMPLE 9 Preparation of2,3,4,5-tetrachloro(p-phenylenedimethylene)-bis(disulfooxoniumdihydroxide)bis(inner salt) from 2,3,5,6-tetrachloro-p-xylene and sulfurtrioxide ##STR22##

The procedure of Example 1 was repeated, except that 24.4 g. of2,3,5,6-tetrachloro-p-xylene, mp. 218°-219° C. was substituted forpentachlorotoluene. The oxidation step of the xylene was apparentlyfaster than that of the toluene as judged by the vigor of the sulfurdioxide evolution on refluxing the purple solution of the radicalcation. After a refluxing period of 0.5 hour only 5% radical cation wasleft in solution, which contained 95% of the dioxonium compound,characterized by the proton nuclear magnetic resonance peaks at 6.36 and9.73 ppm in the correct 2:1 ratio. Distillation of the excess of sulfurtrioxide resulted in a 93% efficiency in its recovery and the isolationof the dioxonium compound in 93% yield. In addition to the nuclearmagnetic resonance data given above the new product was characterizedalso by the quantitative analysis of its hydrolysis products, whichincluded four mole equivalents of sulfuric acid and one mole equivalentof tetrachloro-p-xylene diol as well as by its additional derivatives(see Examples 41 and 47 ).

EXAMPLE 10 Preparation of the dioxonium compound from2,4,5,6-tetrachloro-m-xylene and sulfur trioxide ##STR23##

The procedure of Example 9 was repeated, except that2,4,5,6-tetrachloro-m-xylene, mp. 220°-222° C., eas substituted for thepara isomer. The oxidation of the chlorocarbon occurred readily and wasessentially complete after one hour of refluxing period, when thenuclear magnetic resonance of the purple solution indicated the absenceof any starting material, the presence of only 2.5% of the radicalcation (chemical shift at 4.68 ppm downfield from the referencestetramethylsilane and the presence of the dioxonium compound in 97.5%abundance, as indicated by the chemical shifts at 6.40 and 9.83 ppm inthe correct 2:1 ratio. Further identification of the novel compound wasdone by elemental and spectral analysis of its hydrolysis products,which include, after the stripping of the excess of sulfur trioxide,four moles of sulfuric acid and the formation of one mole equivalent oftetrachloro-m-xylene diol (see Examples 42 and 51).

EXAMPLE 11 Preparation of the dioxonium compound from3,4,5,6-tetrachloro-o-xylene and sulfur trioxide ##STR24##

The procedure of Example 9 was repeated except that3,4,5,6-tetrachloro-o-xylene, mp. 226°-228.5° C., was substituted forthe para isomer. The formation of the radical cation and of thedioxonium compound occurred readily as evidenced by the immediatedevelopment of a deep purple solution and the copious evolution ofsulfur dioxide on heating. Identification of the dioxonium compound wasdone as in the previous examples, except that on hydrolysis only threeequivalent moles of sulfuric acid were produced, in addition to one moleequivalent of the cyclic sulfate of tetrachloro-o-xylene (see Example31). The presence of the dioxonium compound, as shown in the titlestructure, was diagnosed directy by proton nuclear magnetic resonance,which identified the benzylic protons by a singlet at 6.32 ppm and theacidic protons at 9.99 ppm in the correct 2:1 ratio.

EXAMPLE 12 Preparation of the dioxonium compound from2,3,5,6-tetrabromo-p-xylene and sulfur trioxide ##STR25##

The procedure of Example 9 was repeated except that 42.2 g of2,3,5,6-tetrabromo-p-xylene, mp 251.5°-252.8° C., was substituted forthe corresponding tetrachloro compound. The oxidation of thechlorocarbon occurred readily as evidenced by the formation of a deepblue-green slurry, indicative of the radical species, and by theevolution of sulfur dioxide. Proton nuclear magnetic resonance of thesulfur trioxide solution showed even only after one hour of reactiontime, the absence of starting material (by the absence of the methylprotons at 2.79 ppm) and the presence in 98% of the dioxonium compoundby the presence of the benzylic protons at 6.66 ppm and of the acidicprotons at 9.96 ppm in the correct 2:1 ratio, and the presence of only2% of the radical species by a peak at 4.74 ppm. Hydrolysis of thehighly reactive dioxonium compound, a dark, solid product yielded fourmole equivalents of sulfuric acid, as evidenced by titration, and onemole equivalent of 2,3,5,6-tetrabromo-p-xylene-1,4-diol (see Example 29as well as Examples 44 and 45).

EXAMPLE 13 Preparation of the dioxonium compound from2,4,5,6,-tetrabromo-m-xlene and sulfur trioxide ##STR26##

The procedure of Example 12 when applied to 2,4,5,6-tetrabromo-m-xylene,mp 251°-252° C., yielded the corresponding dioxonium compound, asevidenced by its isolation as a reactive solid material in quantitativeyield as well as by its hydrolysis, again in quantitative yield, to fourmole equivalents of sulfuric acid and one mole equivalent of2,4,5,6-tetrabromo-m-xylene-1,3-diol (see Experiment 30).

EXAMPLE 14 Preparation of the dioxonium compound from2,3,5,6-tetraiodo-p-xylene and sulfur trioxide ##STR27##

Repeating the procedure of Example 9 with 61.0 g of2,3,5,6-tetraiodo-p-xylene, mp 245°-247° C., in place of the tetrachloroanalog resulted in the facile oxidation of the iodocarbon and theformation of the dioxonium compound in quantitative yield.

EXAMPLE 15 Preparation of the dioxonium compound from1,3,5,7-tetrabromo-2,6-dimethylnaphthalene and sulfur trioxide ##STR28##

When the procedure described in Example 12 was repeated with thereplacement of the tetrabromoxylene with 47.2 g. of1,3,5,7-tetrabromo-2,6-dimethylnaphthalene, mp 226°-229° C., theformation of the dioxonium compound occurred readiy in the fashiondescribed in the previous examples.

EXAMPLE 16 Preparation of2,4,6-tribromo-s-pheneyltris(methylene)-tris[disulfooxonium]trihydroxidetris (inner salt) from 2,4,6-tribromomestitylene and sulfur trioxide##STR29##

The procedure described in Example 12 was repeated, except that thetetrabromo-p-xylene was replaced with 35.7 g of2,4,6-tri-bromomesitylene, mp 215°-217° C. A very facile oxidation ofthe bromocarbon occurred with copious evolution of sulfur dioxides,resulting in the formation of the trioxonium compound in quantitativeyield.

EXAMPLE 17 Preparation of the dioxonium compound from2,3,5,6-tetrachloro-p-xylene-1,4-diol and sulfur trioxide ##STR30##

The dissolution of 27.6 g of 2,3,5,6-tetrachloro-p-xylene-1,4-diol in100 ml (197 g) of liquid sulfur trioxide took place without theevolution of sulfur dioxide, which did not commence even after 3 hoursof refluxing. Stripping of the excess of sulfur trioxide resulted in theisolation of the dioxonium compound identical with the one obtained inExample 9.

EXAMPLE 18 Preparation of 2,3,5,6-tetrachloro(p-phenylenedimethylene)bis[(chlorosulfonyl)sulfooxonium]dihydroxidebis(inner salt from α,α',2,3,5,6-hexachloro-p-xylene and sulfur trioxide##STR31##

The procedure of Example 3 was repeated except that 31.3 g of aα,α',2,3,5,6-hexachloro-p-xylene, mp 179°-181° C., was substituted forpentachlorobenzyl chloride. Although a deep purple solution was formed,no evolution of sulfur dioxide occurred. The deep purple component ofthe reaction mixture was identified as the benzylic radical by itsnuclear magnetic resonance peak at 4.69 ppm whereas the dioxoniumcompound was also identified by its chemical shift at 6.41 ppm, as wellas by its hydrolysis in quantitative yield to four equivalent moles ofsulfuric acid, two equivalent moles of hydrochloric acid and oneequivalent mole of 2,3,5,6-tetrachloro-p-xylene-1,4-diol (see Example69).

EXAMPLE 19 Preparation of the dioxonium compound fromα,α',3,4,5,6-hexachloro-o-xylene and sulfur trioxide ##STR32##

The procedure of Example 3, when applied to 31.3 g ofα,α',3,4,5,6-hexachloro-o-xylene, mp 92°-92.5° C., yielded an intenselypurple solution but essentially no sulfur dioxide evelution even duringa refluxing period of 3 hours. The intermediate biradical was identifiedby its nuclear magnetic resonance peak at 4.65 ppm (present in about8-10% abundance in the reaction mixture), whereas the dioxonium compound(90-92% of the reaction mixture) had the chemical shift of its protonsat 6.31-6.33 ppm. After the stripping of the excess of sulfur trioxide,the dioxonium compound was obtained as a dark amber colored viscous oilin quantitative yield (63.5 g) and was further identified by itshydrolysis to three mole equivalents of sulfuric acid, two moleequivalents of hydrochloric acid and one mole equivalent of the cyclicsulfate of 3,4,5,6-tetrachloro-o-xylene-1,2-diol (see Example 32).

EXAMPLE 20 Preparation of a transient oxonium compound from2,3,4,5,6-pentachloroethylbenzene and sulfur trioxide ##STR33##

The procedure of Example 1 was repeated, except that 27.8 g (0.1 mole)of 2,3,4,5,6-pentachloroethylbenzene, mp 56°-57° C., was substituted forpentachlorotoluene. Oxidation of the chlorocarbon was evidenced by theformation of the colored (deep purple) radical cation, by the evolutionof sulfur dioxide as well as by hydrolysis experiment (see Example 62).

Although the transient oxonium product of this experiment was notisolated, its structure may be infered by consideration of the reactantsand the product of Example 62, infra. Likewise, the material balancebased upon SO₂ evolution evidenced the formation of the oxonium saltdepicted supra.

The following examples illustrate the usefulness of the oxoniumcompounds for the preparation of a large variety of novel as well asknown halogen containing compounds in simple reactions and in highconversions.

EXAMPLE 21 Preparation of the sodium salt of pentachlorobenzyl hydrogensulfate ##STR34##

The oxonium salt prepared in Example 1 was added gradually and withcooling to 1 liter of 75:25 (vol/vol) mixture of water and ethylalcohol. After filtration to the resultant solution there was added 200ml of a 1.0 normal aqueous sodium hydroxide solution, whereby a whitecrystalline salt separated out of the solution and was identified as thetitle compound by elemental analysis and nuclear magnetic resonance.

Calculated for C₇ H₂ Cl₅ NaO₄ S. 1/2H₂ O: C, 21.5; H, 0.77; Cl, 45.3; S,8.2%; Found: C, 21.6; H, 0.8; Cl, 43.2; S, 8.5%.

Nuclear magnetic resonance in dimethyl sulfoxide (DMSO) showed a singletmethylene at 5.05 ppm (area 2) and a water peak at 3.30 ppm (area 1.).

EXAMPLE 22 Preparation of the ammonium salt of pentachlorobenzylhydrogen sulfate ##STR35##

The procedure of Example 21 was repeated, except that the reactionproduct obtained in Example 3 was added to a concentrated solution ofaqueous ammonium hydroxide. The title compound, which crystallized out,was isolated by filtration in 42% conversion and was identified byelemental analysis and by its proton nuclear magnetic resonancespectrum.

Calculated for C₇ H₆ Cl₅ NO₄ S. 1/2H₂ O: C, 21.3; H, 1.8; Cl, 44.2; N,3.7; S, 8.9%. Found: C, 21.7; H, 1.8; Cl, 45.8; N, 3.6; S, 8.8%.

Nuclear magnetic resonance (in DMSO) showed a singlet methylene at 5.09ppm and a broad band at 7.1-7.4 ppm corresponding to the protons of theammonium cation.

EXAMPLE 23 Preparation of 2,3,4,5,6-pentachlorobenzyl alcohol ##STR36##

The light greenish, solid residue obtained by repeating the procedure ofExample 1, was added to 500 ml of water, followed by heating theresultant white aqueous slurry to reflux for 15 minutes. Filtrationyielded a white, powdery material, which after filtration, washing anddrying weighed 26.6 g. Its purification was effected by refluxing itwith 150 ml of glacial acetic acid, containing a trace of sulfuric acid,for a period of 20 minutes, followed by filtration of a small amount(2.7 g) of insoluble material, identified below. Excess of acetic acidwas distilled off from the filtrate and the resultant solid residue wasrefluxed for 30 minutes with 200 ml of 10% methanolic potassiumhydroxide solution. The resultant reaction mixture was poured into waterand the solid precipitate was filtered. Washing with water andsubsequent dryings yielded 24.5 g of pure 2,3,4,5,6-pentachlorobenzylalcohol, mp 195.0°-196.5° C., which corresponds to 91% yield.Confirmation of its structure was done by comparison of its infra-redand nuclear magnetic resonance spectral properties with those of anauthentic specimen, as well as by mixed melting point. A dilute DMSOsolution of the experimental sample showed a doublet at 4.74 ppm,corresponding to the benzylic protons and a triplet at 5.50 ppm (at 34°C.; and 5.39 ppm at 60° C.) corresponding to the hydroxylic proton. Themultiplicity is caused by mutual coupling with a J value of circa 5.5cps. The two multiplets were present in the correct 2:1 ratio of thecorresponding areas.

The 2.7 g of material found insoluble in acetic acid was separated bytrituration with hot toluene into a soluble fraction and an insolublefraction. The hot toluene solution on cooling yielded 1.75 g of a whitecrystalline material, identified as decachlorodibenzyl ether, mp223°-225° C., by infra-red, nuclear magnetic resonance, and mixedmelting point of an authentic specimen. Its infra-red spectrum,determined in tetrachloroethylene and carbon disulfide solutions, hadstrong maxima at 1365, 1232, 1125, 1078 and 682 cm⁻¹. Its proton nuclearmagnetic resonance spectrum displayed a singlet at 4.92 ppm, asdetermined in deuteriochloroform solution.

The 0.5 g of the hot toluene insoluble material was identified byinfra-red, nuclear magnetic resonance and mass spectroscopy as a mixtureof 2,3,4,5,6,2',3',4',5',6'-decachlorodiphenylmethane (0.25 g),2,4,5,6,2',3',4',5',6'-nonochloro-3-methyldiphenylmethane (0.12 g) and2,3,5,6,2',3',4',5',6'-nonachloro-4-methyldiphenylmethane (0.13 g).

Similar, almost identical, results to these were obtained also when theresidues of Experiments 2 and 3 were worked up by the procedure outlinedin Example 23.

EXAMPLE 24 Preparation of the disodium salt of2,3,5,6-tetrachloro-p-xylene-α,α'-diol dihydrogen sulfate ##STR37##

When the dark residue obtained after the stripping of unreacted sulfurtrioxide in Example 9 was added to a mixture of ice and saturated sodiumchloride solution, a white solid was formed, which after filtration andair drying weighed 24.1 g. Recrystallization from water gave ananalytically pure sample of the title compound with a characteristicproton nuclear magnetic resonance singlet of the benzylic protons at5.13 ppm and the water protons at 3.40 ppm, in DMSO solution.

Calculated for C₈ H₄ Cl₄ Na₂ O₈ S₂.2H₂ O: C, 18.64; H, 1.56; Cl, 27.41;H₂ O, 7.01%. Found: C, 19.0; H, 1.4; Cl, 28.7; H₂ O, 7.3%.

EXAMPLE 25 Preparation of 2,3,5,6-tetrachloro-p-xylene-α,α'-diol##STR38##

When the dioxonium compound obtained in Example 9 was added to ice andthe resultant white slurry was refluxed with an equal amount of 20%aqueous hydrochloric acid solution, a readily filtrable whiteprecipitate was obtained, which was washed with water and dried.Recrystallization from dioxane yielded white crystals, mp 226°-230°,found to be identical by mixed melting point, infra-red and nuclearmagnetic resonance with authentic2,3,5,6-tetrachloro-p-xylene-α,α'-diol.

The infra-red spectrum of the pure diol, ran in FLUOROLUBE and mineraloil mull had maxima at 3200, 1350, 1240, 1185, 1130, 1035, 1018, 950,828, 690, 650 and 525 cm⁻¹. The nuclear magnetic resonance spectrum of aDMSO solution displayed the methylene protons as a doublet at 4.67 ppmand the hydroxylic proton at 5.32 ppm as a triplet.

An alternate workup of the residue of Experiment 9 yields the dioldirectly. It consists of adding the dark residue to ice and heating theresultant slurry on the steam bath until the hydrolysis of the hydrogensulfate ester is essentially complete. Filtration of the slightlyoff-white precipitate and washing it with water results, even withoutrecrystallization, in a nearly quantitative yield of the pure diol.

EXAMPLE 26 Preparation of the disodium salt of2,4,5,6-tetrachloro-m-xylene-α,α'-diol dihydrogen sulfate ##STR39##

When the dark, almost black, residue of Experiment 10 was added to iceand neutralized with 400 ml of ice cold 10% sodium hydroxide solution, aclear solution of the sodium salt of the sulfuric acid ester resulted.Evaporation of all of the free water yielded 104.8 g of a slightlypinkish solid, the proton nuclear magnetic resonance spectrum of which,in DMSO solution, indicated it to be predominatly the title compound bythe presence of the benzylic protons at 5.07 ppm (the reaction mixture,obtained after the stripping of water, contains, as indicated by thestoichiometry, also 2 mole equivalents of hydrated sodium sulfate).Elution with hot methanol (1000 ml) left behind much of the inorganicsalt, but the isolation of an analytically pure organic sample was notachieved, due to the high solubility of this compound in water.

EXAMPLE 27 Preparation of 2,4,5,6-tetrachloro-m-xylene-α,α'-diol##STR40##

The process of Example 26 was repeated and the solid product (104.8 g)was dissolved in 325 ml of water and acidified with 110 ml ofconcentrated hydrochloric acid, evaporation of the volatile inorganicmaterials left behind 132 g of residue, which after water wash,filtration and drying yielded 22.3 g or 81% of pure2,4,5,6-tetrachloro-m-xylene-α,α'-diol, mp 228°-230° C., whose identitywas corroborated by its infra-red and nuclear magnetic resonancespectra, as well as by mixed melting point. Thus its infrared spectrum(run in Nujol mull) had maxima at 3250, 1430, 1350, 1310, 1265, 1250,1110, 1015, 965, 895, 652, 542 and 475 cm⁻¹ ; the nuclear magneticresonance spectrum ran in DMSO, contained the benzylic hydrogens as adoublet at 4.72 ppm and the hydroxylic protons as a triplet at 5.37 ppm.

EXAMPLE 28 Preparation of the disodium salt of2,3,5,6-tetrabromo-p-xylene-α,α'-diol bis(hydrogen sulfate) ##STR41##

The dark solid residue obtained in Example 12 was added in smallportions to ice water, parallel with the addition of an ice cold, 10%aqueous sodium hydroxide solution maintaining the pH slightly on thealkaline side. A total of 360 ml of the base was required. Filtration,followed by washing with ice water, yielded a filter cake, which afterdrying weighed 60.6 g or approximately 92% of the theoretical amount.Nuclear magnetic resonance spectroscopy confirmed its structure by thecorrect chemical shift of the benzylic protons at 5.23 ppm (DMSOsolution).

EXAMPLE 29 Preparation of 2,3,5,6-tetrabromo-p-xylene-α,α'-diol##STR42##

The solid residue of the stripping of sulfur trioxide in Example 12, wasadded to an excess (500 ml) of ice water, allowing the temperature torise gradually. The resultant slurry was stirred mechanically and heatedat reflux for one-half hour. Filtration and thorough washing of thefiltercake yielded after drying, 41.2 g of a slightly off white product,which corresponds to 91% yield. Recrystallization from dioxane yieldedoff white crystals, mp 248°-252° C., whose infrared (maxima in Nugolmull at 3280, 1330, 1257, 1237, 1162, 1096, 1020, 983, 945, 812, 648,575, 545 and 490 cm⁻¹) and nuclear magnetic resonance spectra (benzylicprotons at 4.93 ppm; hydroxylic protons at 5.23 ppm in DMSO solution)confirmed its structure.

Calculated for C₈ H₆ Br₄ O₂ : C, 21.17; H, 1.33; Br, 70.44%. Found: C,20.8; H, 0.9; Br, 70.0%

EXAMPLE 30 Preparation of 2,4,5,6-tetrabromo-m-xylene-α,α'-diol##STR43##

Repeating the procedure of Example 29 with the residue of Example 13yielded the title compound in 93% yield; mp 248°-252° C. Infrared maximain Nujol mull were at 3280, 1525, 1340, 1310; 1260, 1225, 1212, 1196,1068, 1032, 1028, 996, 965, 952, 838, 625, 603 and 487 cm⁻¹, and nuclearmagnetic resonance showed the benzylic protons at 4.95 ppm in DMSOsolution.

Calculated for C₈ H₆ Br₄ O₂ : C, 21.17, H, 1.33; Br, 70.44%. Found: C,21.0; H, 1.1; Br, 69.9%.

EXAMPLE 31 Preparation of the cyclic sulfate of3,4,5,6-tetrachloro-o-xylene-α,α'-diol ##STR44##

The dark pasty residue of Example 11 was added in portions to ice. Thereaction was highly exothermic and yielded a rust colored product, whichwas filtered off, washed with water (or dilute aqueous sodium hydroxide)until it became free of acid. The product weighed 32.0 g or 95% of thetheory. Recrystallization (twice) from trichloroethylene yielded yellowcrystals, mp 186.0°-188.5° C., whose structure as the cyclic sulfate wasconfirmed by elemental analysis, molecular weight determination,infra-red and nuclear magnetic resonance spectroscopy.

Calculated for C₈ H₄ Cl₄ O₄ S: mol. wt, 338.01; C, 28.43; H, 1.19; Cl,41.96; S, 9.49%. Found: mol. wt., 338 (by vapor phase osmometry,tetrahydrofuran solvent); C, 28.8; H, 1.2; Cl, 43.0; S, 9.8%.

Infrared maxima in C₂ Cl₄ and CS₂ solutions occurred at 1420, 1380,1330, 1308, 1278, 1212, 1198, 1176, 1031, 1004, 975, 950, 840, 658, 650,645, 574, 566, 525, 514, 484 and 450 cm⁻¹.

Nuclear magnetic resonance (deuteriochloroform solution) displayed asinglet at 5.65 ppm, downfield from tetramethylsilane.

When worked up with neutralization by sodium hydroxide solution, thepasty solid of Example 11 occasionally yielded also smaller amounts oftetrachlorophthalan, mp. 214°-216° C. a known compound, identifiablereadily in admixture with the cyclic sulfate, by the presence of asinglet at 5.12 ppm in its nuclear magnetic resonance spectrum,attributable to the benzylic protons.

EXAMPLE 32 Preparation of the cyclic sulfate of3,4,5,6-tetrachloro-o-xylene-α,α'-diol ##STR45##

Addition of the distillation residue of Example 19 to ice or to ice colddilute aqueous sodium hydroxide solution resulted in the formation ofthe cyclic sulfate described and identified in Example 31.

EXAMPLE 33 Preparation of pentachlorobenzaldehyde ##STR46##

The addition of the dark dioxonium compound of Example 6 to 500 g ofice, followed by short heatings to 85° C. and filtration of the warmslurry, followed by water wash and drying resulted in the isolation of26.6 g of a yellowish powdery material, shown to be purepentachlorobenzaldehyde by gas chromatography, by nuclear magneticresonance and infra-red spectroscopy. Recrystallization fromchlorobenzene yielded pale yellow crystalline material, mp 201°-203° C.,undepressed by the addition of authentic pentachlorobenzaldehyde. Itsinfrared spectrum, run in tetrachloroethylene and carbon disulfidesolution, contained characteristic maxima at 2850, 1715, 1525, 1345,1310, 1232, 1220, 1190, 1128, 946, 692, 659 and 522 cm⁻¹ ; its nuclearmagnetic resonance spectrum displayed the aldehydic proton as a singletat 10.32 ppm (deuteriochloroform solution) or at 10.26 ppm (inhexadeuteriodimethylsulfoxide).

EXAMPLE 34 cl Preparation of pentachlorobenzaldehyde ##STR47##

A workup similar to that of the preceding Example with the residue ofExample 8 yielded again pentachlorobenzaldehyde, mp. 201°-203° inessentially quantitative conversion. The product was not contaminated byeven traces of pentachlorobenzoic acid.

EXAMPLE 35 Preparation of pentabromobenzaldehyde ##STR48##

Addition of the dark residue of Example 7 to 500 g of ice, followed byshort heating at 75°, filtration, washing and drying, resulted in theformation of 49.0 of a light brown powder, shown by gas chromatographyto be 97.1% pure pentabromobenzaldehyde. The yield accordingly was94.5%. Recrystallization from chlorobenzene improved the color andyielded the pure aldehyde in form of a light, cream colored, finelycrystalline material, mp. 281°-283°, identified also by infra-red andnuclear magnetic resonance. Even the crude product was very pure and wasfree of pentabromobenzoic acid. Infrared analysis of the pure aldehydein C₂ Cl₄ and CS₂ solution showed maxima at 2840, 1720, 1300, 1250,1170, 1068, 896 and 558 cm⁻¹ ; its nuclear magnetic resonance spectrumdisplayed the single proton at 9.81 ppm in DMSO and at 9.13 ppm inhexadeuteriobenzene solution.

EXAMPLE 36 Preparation of α,2,3,4,5,6-hexachlorotoluene ##STR49##

The gradual addition with cooling of an excess (400 ml) of carbontetrachloride to the oxonium compound prepared in Example 1 resulted inan exothermic reaction accompanied by strong gas evolution (phosgene andgaseous hydrochloric acid; good ventilation or, preferably, theabsorption of the exit gases in strong aqueous alkali solution isrecommended). After the addition was completed the resultant purplishsolution was heated to reflux temperature (76°-80° C.) and kept therefor twenty minutes. An additional amount of gas evolved during thisperiod. Solid, anhydrous sodium carbonate was added to the reactionmixture in small portions until the evolution of carbon dioxidesubsided. The resultant amber colored slush was filtered, rinsed withcarbon tetrachloride, the solution was stripped of solvent on a rotatingevaporator, yielding an amber liquid. This, added to ice, turned paleyellow and was filtered by suction and dried. Its structure aspentachlorobenzyl chloride (α,2,3,4,5,6-hexachlorotoluene) wasestablished by its melting point (100°-101° C.) infrared and nuclearmagnetic resonance, and its weight of 29.0 g indicated a 98% yield.

Infrared spectrum of the product, run in tetrachloroethylene and carbondisulfide solution, had maxima at 1355, 1302, 1272, 1240, 1128, 958,926, 766, 698, 682, 608 and 495 cm⁻¹. Its nuclear magnetic resonancedisplayed the benzylic hydrogen as a singlet at 4.86 ppm, indeuteriochloroform solution.

EXAMPLE 37 Preparation of α,2,3,4,5,6-hexachlorotoluene ##STR50##

When chloroform was added, gradually and with external cooling to thesolid residue of Example 1, followed by fifteen minutes refluxing andworkup as described in Example 36, a high yield (circa 70 percent) ofthe title compound resulted.

EXAMPLE 38 Preparation of α,α,2,3,4,5,6-heptachlorotoluene ##STR51##

Repeating the procedure of Example 36 with the distillation residue ofExample 6, instead of Example 1, resulted in the formation ofα,α,2,3,4,5,6-heptachlorotoluene, (pentachlorobenzal chloride), mp.118°-119° C. Its infrared spectrum, run in tetrachloroethylene andcarbon disulfide solution, displayed maxima at 3045, 1540, 1352, 1278,1232, 1227, 1127, 962, 776, 762, 712, 680, 614 and 506 cm⁻¹ and itsnuclear magnetic resonance spectrum consisted of a single peak at 7.55ppm in deuteriochloroform solution.

EXAMPLE 39 Preparation of α-bromo-2,3,4,5,6-pentachlorotoluene ##STR52##

The procedure of Example 36 was repeated, except that a solution of 35.0g (0.11 mole) of carbon tetrabromide in 100 ml. of tetrachloroethylenewas substituted for carbon tetrachloride. Workup by the same procedureyielded, after evaporation of the solvent, 64.6 g of a yellow,crystalline material, subsequently shown to be a mixture ofα-bromo-2,3,4,5,6-pentachlorotoluene (pentachlorobenzyl bromide) and1,2-dibromotetrachloroethane. The yield of these materials thus amountedto 94.5%. Repeated recrystallization from ethanol yielded the benzylbromide as the less soluble component, mp. 109.5-112.5, undepressed bymixed melting point of an authentic sample. Infrared maxima occurred at1535, 1430, 1326, 1291, 1236, 1225, 1122, 955, 887, 871, 758, 732, 695,678, 650, 558 and 485 cm⁻¹, in tetrachloroethylene and carbon disulfidesolution. Its nuclear magnetic resonance spectrum in deuteriochloroformsolution presented a singlet at 4.74 ppm.

Calculated for C₇ H₂ BrCl₅ : C, 24.49; H, 0.58; Br, 23.28; Cl, 51.64%;Found: C, 22.4; H, 0.6; Br, 23.2; Cl, 51.6%.

The mother liquor of the recrystallization was evaporated to dryness andthe residue dissolved in pentane, treated with charcoal, filtered andrecrystallized from methanol to yield white crystals, melting withdecomposition at 138° C. Its infrared spectrum showed maxima at 810,760, 720, 636 and 615 cm⁻¹.

Calculated for C₂ Br₂ Cl₄ : mol. wt. 325.67: C, 7.38; Br, 49.07. Found:mol. wt. 330, by vapor pressure osmometry in chloroform solution C,7.38; Br, 45.8%

EXAMPLE 40 Preparation α-iodo-2,3,4,5,6-pentachlorotoluene ##STR53##

Repeating the procedure of Example 36 except that a saturated solutionof a slight excess of iodoform in methylene chloride was substituted forcarbon tetrachloride, resulted, after a similar workup, in the isolationof a pure sample of the title compound, called also pentachlorobenzyliodide, in form of light yellow glistening flakes, which afterrecrystallization from cyclohexane, had mp 138.5°-140.5° C. Its infraredspectrum contained maxima at 1540, 1424, 1360, 1318, 1232, 1160, 1119,1104, 953, 836, 756, 729, 678, 512 and 478 cm⁻¹, while the resonance ofthe benzylic protons in its nuclear magnetic resonance spectrum occurredat 4.65 ppm in deuteriochloroform solution.

Calculated for C₇ H₂ Cl₅ I: C, 21.54; H, 0.52; Cl, 45.42; I, 32.51.Found: C, 21.6; H, 0.5; Cl, 45.4; I, 32.5%.

EXAMPLE 41 Preparation of α,α',2,3,5,6-hexachloro-p-xylene ##STR54##

Repeating the procedure illustrated in Example 36 with the pasty residueof Example 9 resulted in the isolation of 30.3 g of yellow solids, whichafter recrystallization from carbon tetrachloride yielded whitecrystals, mp 179°-182°, in 28.1 g yield. Infrared, nuclear magneticresonance, elemental analysis and mixed melting point showed that theproduct of this reaction was the title compound, which was obtained in90% yield. Its infrared peaks occurred at 1436, 1372, 1362, 1269, 1251,1147, 914, 837, 745, 685, 660, 632, 609, 490 and 460 cm⁻¹, and itsnuclear magnetic resonance spectrum displayed the benzylic protons as asinglet at 4.89 ppm in deuteriochloroform solution.

Calculated for C₈ H₄ Cl₆ : C, 30.71; H, 1.29; Cl, 68.00%. Found: C,30.6; H, 1.3; Cl, 68.2%.

EXAMPLE 42 Preparation of α,α',2,4,5,6-hexachloro-m-xylene ##STR55##

Repeating the procedure of Example 41 with the residue obtained inExample 10 resulted in the isolation of the title compound, mp 136°-138°C. in 92% yield. Spectral parameters: infrared, 1555, 1448, 1398, 1376,1278, 1268, 1160, 1129, 1010, 932, 910, 906, 770, 752, 730, 682, 618,608, 604, 540, 530, 446 and 436 cm⁻¹ ; nuclear magnetic resonanceabsorption at 4.86 ppm in CDCl₃ solution.

Calculated For C₈ H₄ Cl₆ : C, 30.71; H, 1.29; Cl, 68.00%. Found: C,30.5; H, 1.3; Cl, 68.3%.

EXAMPLE 43 Preparation of α,α',3,4,5,6-hexachloro-o-xylene ##STR56##

When the procedure of Example 41 was repeated except that the reactionwith carbon tetrachloride was carried out with the product of Example11, a 94% yield of the title compound was realized. Afterrecrystallization from methanol the pure compound had mp 84.0°-84.7° C.;infrared maxima were found at 2998, 2898, 1550, 1480, 1450, 1400, 1375,1278, 1270, 1240, 1196, 1153, 951, 940, 890, 723, 716, 692, 612, 609,532 and 462 cm⁻¹, ran in C₂ Cl₄ and CS₂ solutions; nuclear magneticresonance peak as a singlet occurred at 4.85 ppm in deuteriochloroformsolution.

Calculated for C₈ H₄ Cl₆ : C, 30.71; H, 1.29; Cl, 68.00%. Found: C,30.7; H, 1.3; Cl, 67.8%.

EXAMPLE 44 Preparation of 2,3,5,6-tetrabromo-α,α'-dichloro-p-xylene.##STR57##

Repeating the procedure of Example 41 except that the product of Example12 was used to react with carbon tetrachloride, a nearly quantitativeyield of the title compound, mp 232°-233° C. was obtained. Its infraredmaxima were at 1435, 1350, 1330, 1265, 1237, 1134, 1104, 904, 740, 625,597 and 544 cm⁻¹ : nuclear magnetic resonance displayed the benzylicprotons as a singlet at 5.11 ppm in deuteriochloroform solution.

EXAMPLE 45 Preparation of α,α',2,3,5,6-hexabromo-p-xylene ##STR58##

Repeating the procedure of the previous Example except that an excess ofcarbon tetrabromide, instead of carbon tetrachloride, was added to thedioxonium compound, a 90% yield of the title compound was obtained, mp207.5°-270.8° C. Characteristic maxima in its infrared spectrum occurredat 1104, 868 and 638 cm⁻¹, the paucity of the bands being due to thepoor solubility of the compound in infrared solvents. Its nuclearmagnetic resonance singlet of the benzylic protons was found at 4.79 ppmin CDCl₃ solution.

Calculated for C₈ H₄ Br₆ : C, 16.52; H, 0.70; Br, 82.78%. Found: C,16.4; H, 0.6; Br, 82.1%.

EXAMPLE 46 Preparation of 2,3,4,5,6-pentachlorodiphenylmethane ##STR59##

The addition of the oxonium compound prepared in Example 1 to 200 ml ofbenzene, with cooling and stirring, followed by the addition of water,separation of the two layers and stripping of the excess of benzeneresulted in the isolation of a light brown solid, 28.8 g, which, afterrecrystallization from ethanol and hexane, yielded white needles, mp112.5°-113.5° C. Elemental analysis, infrared and nuclear magneticresonance indicated that the product of this reaction is thepentachlorodiphenylmethane indicated in the title. The yield,accordingly, was 83%. The infrared maxima occurred at 3075, 3052, 3022,2928, 2840, 1601, 1542, 1495, 1450, 1438, 1360, 1352, 1337, 1310, 1282,1230, 1180, 1118, 1112, 1072, 1038, 946, 884, 776, 726, 692, 678, 638,618, 602, 540, 522 and 448 cm⁻¹ in C₂ Cl₄ and CS₂ solution. Themethylene protons in the nuclear magnetic resonance scan in CDCl₃solution were at 4.37 ppm as a singlet and the aromatic protons at 7.18ppm as multiplets in the correct 2:5 area ratio.

Calculated for C₁₃ H₇ Cl₅ : C, 45.85; H, 2.07; Cl, 52.07%. Found: C,45.9; H, 2.1; Cl, 51.1%.

EXAMPLE 47 Preparation of 2,3,5,6-tetrachloro-α,α'-diphenyl-p-xylene##STR60##

When the dioxonium compound prepared in Example 9 was added portionwiseand with cooling to an excess (200 ml) of benzene and the reactionmixture was worked up as in the preceding example, there was obtained21.6 g of a yellow solid, which after recrystallization from carbontetrachloride, had up 179.5°-181.0° C. Infrared, nuclear magneticresonance and elemental analysis confirmed its structure as thatindicated in the title of this example. The infrared parameters, run inC₂ Cl₄ and CS₂ solutions, were at 3075, 3052, 3022, 2922, 2835, 1600,1498, 1452, 1430, 1390, 1370, 1282, 1250, 1158, 1133, 1100, 1072, 1029,932, 883, 729, 693, 654, 618, 580, 524, 500 and 447 cm⁻¹. The benzylichydrogens were found to resonate in CDCl₃ solution at 4.41 ppm and thearomatic protons at 7.20 ppm (as multiplets) in the correct 2:5 arearatio.

Calculated for C₂₀ H₁₄ Cl₄ : C, 60.60; H, 3.53; Cl, 35.87%. Found: C,60.7; H, 3.6; Cl, 35.7%.

EXAMPLE 48 Preparation of 2-chloro-3-pentachlorophenylpropanoic acid##STR61##

When the procedure of Example 1 was repeated and an excess (100 ml) oftrichloroethylene was added to the resultant oxonium compound withcooling and stirring. After circa 20 minutes of reaction time themixture was poured into water and the excess of solvent was removedunder vacuum from the organic phase. There was obtained 34.2 g of awhite solid, which after recrystallization melted at 170.0°-172.5° C.Its infrared spectrum in mineral oil mull had maxima at 1722, 1424,1350, 1318, 1292, 1268, 1230, 1195, 1168, 1118, 1058, 956, 943, 928,890, 775, 765, 724, 690, 680, 632, 628, 598, 514 and 497 cm⁻¹, and itsnuclear magnetic resonance spectrum in DMSO solution displayed thebenzylic protons as a doublet at 3.66 ppm and the single proton adjacentto the carboxyl as a triplet at 4.77 ppm, with J being 7 cps.

Calculated for C₉ H₄ Cl₆ O₂ : C, 30.29; H, 1.13; Cl, 59.63. Found: C,30.1; H, 1.1; Cl, 59.2%.

EXAMPLE 49 Preparation of 2-chloro-3-pentachlorophenylpropanoic acid##STR62##

To the oxonium compound produced in Example 3 there was added 10 ml ofsulfuric acid prior to the addition of trichloroethylene (150 ml), whichwas carried out with cooling by ice. Workup as in the preceding exampleresulted in the isolation of 35.6 g (quantitative yield) of the acididentical with that of the preceding example.

EXAMPLE 50 Preparation of 2,3,5,6-tetrachloro-p-benzenebis(2-chloropropionic acid) ##STR63##

When the dioxonium compound prepared in Example 9 was mixed with 20 mlof concentrated sulfuric acid and the resultant mixture was added to 100ml of trichloroethylene, followed by stirring at room temperature forone hour and heating to reflux for another hour, treatment with ice,separation, drying and removal of the excess of solvent by strippingunder reduced pressure, there was obtained 42.3 g of the title compoundcorresponding to 99% yield, melting, after recrystallization fromortho-chlorotoluene, between 240° and 250° C., with decomposition. Itsnuclear magnetic resonance spectrum ran in hexadeuterioacetone, showedthe benzylic protons as a doublet at 3.85 ppm and the adjacent proton asa triplet at 4.88 ppm, with a coupling constant of 8 cps.

Calculated for C₁₂ H₈ Cl₆ O₄ : C, 33.57; H, 1.87; Cl, 49.58%. Found: C,33.5; H, 2.0; Cl, 47.1%.

The reaction of the dioxonium compound with trichloroethylene isvisualized as an addition (or insertion) reaction involving again anoxonium compound (50A) represented by the following equation ##STR64##Support for the structure of 50A was obtained from its nuclear magneticresonance spectrum, which was run prior to its hydrolysis to thedipropionic acid named in the title. The nuclear magnetic resonancespectrum of 50A in trichloroethylene solution contained the benzylicprotons as a doublet at 4.39 ppm, the adjacent single proton as atriplet at 5.58 ppm with a coupling constant of 7 cps; and the acidicprotons as a singlet at 5.03 ppm. Hydrolysis of 50A to the title productinvolves the transformation of the geminal chlorines into a carbonylfunction, thus yielding the organic acid end product.

EXAMPLE 51 Preparation of 2,4,5,6-tetrachloro-m-benzenebis(2-chloropropionic acid ##STR65##

Repeating the procedure of the preceding example with the dioxoniumcompound obtained in Example 10, there was obtained a quantitativeyield, 42.9 g of the title compound, mp 196°-199° C. Its infraredcontained maxima in Nujol mull at 1730, 1692, 1330, 1288, 1279, 1252,1212, 1172, 1110, 965, 955, 929, 780, 750, 720, 700, 603, 54 and 470cm⁻¹ and its nuclear magnetic resonance spectrum, run inhexadeuterioacetone, displayed the benzylic protons as a doublet at 3.78ppm, the adjacent single proton as a triplet at 4.83 ppm, with acoupling constant of 8 cps.

Calculated for C₁₂ H₈ Cl₆ O₄ : C, 33.57; H, 1.87; Cl, 49.58%. Found: C,33.9; H, 210; Cl, 49.6%.

EXAMPLE 52 Preparation of 3,4,5,6-tetrachloro-o-benzenebis(2-chloropropionic acid ##STR66##

Repeating the procedure of Example 50, except that the dioxoniumcompound obtained in Example 11 was utilized, there was obtained 27.0 gor 63% of the title compound, mp 250°-252° recrystallized from diethylether. Its infrared spectrum, obtained as a mineral oil mull, had maximaat 1750, 1724, 1370, 1308, 1268, 1225, 1172, 1150, 1055, 942, 805, 745,698, 663, 620 and 538 cm⁻¹ and its nuclear magnetic resonance spectrumwhich was complex, showed the four benzylic protons at 3.8 ppm, theadjacent protons at 4.7 ppm.

Calculated for C₁₂ H₈ Cl₆ O₄ : C, 33.57; H, 1.87% Found: C, 33.7; H,1.9%.

EXAMPLE 53 Preparation of 2,4,5,6-tetrabromo-m-benzenebis(2-chloropropionic acid) ##STR67##

Applying the procedure described in Example 50 to the dioxonium compoundobtained in Example 13, resulted in the formation and isolation of thetitle compound, mp 205°-212°, in 36.4 g or 60% yield.

EXAMPLE 54 Preparation of 2,3,5,6-tetrachloro-p-benzenebis(2-chloropropionic acid ##STR68##

Repeating the procedure of Example 50 with the dioxonium compoundobtained in Example 18 resulted in the essentially quantitativeformation (42.0 g) of the title compound, found to be identical with theproduct characterized in Example 50.

EXAMPLE 55 Preparation of 2,2-dichloro-3-phenylpropanoic acid ##STR69##

When the procedure of Example 48 was repeated, except thattetrachloroethylene, instead of trichloroethylene, was added to theoxonium compound, workup as described, resulted in the isolation of 40.0grams of an off white solid. Its nuclear magnetic resonance spectrumindicated the presence of 5% of pentachlorobenzyl chloride, 3% of2-chloro-3-pentachloro-phenyl propenoic acid and 92% of the titlecompound. Trituration with hexane and recrystallization from benzeneyielded white crystals, mp 173°-176°, shown by infrared, nuclearmagnetic resonance and elemental analysis to be the pure title compound.Its infrared spectrum, obtained as a mineral oil mull, had maxima at1722, 1425, 1360, 1325, 1262, 1250, 1230, 1112, 1042, 979, 958, 932,864, 774, 725, 700, 672, 653, 640, 600, 542, 520 and 460 cm⁻¹ ; itsnuclear magnetic resonance run in DMSO, displayed the benzylic protonsas a singlet at 4.31 ppm.

Calculated for C₉ H₃ Cl₇ O₂ : C, 27.64; H, 0.77; Cl, 63.43%. Found: C,27.8; H, 0.8; Cl, 63.5%.

EXAMPLE 56 Preparation of α, 2,3,4,5,6-hexachlorocinnamic acid ##STR70##

When the procedure of the preceding example was repeated, but thetetrachloroethylene solution was heated to reflux for half an hour,workup as before yielded 28.0 g of a crude product, whose nuclearmagnetic resonance spectrum, ran in hexadeuterioacetone, indicated thepresence of both the propenoic acid (major) and the propanoic acid.Recrystallization from tetrachloroethylene yielded 23.1 g (68% yield) ofthe pure title compound, mp 242°-243° C. Its infrared spectrum in Nujolmull had maxima at 1715, 1698, 1525, 1426, 1348, 1328, 1300, 1260, 1241,1220, 1125, 1032, 955, 908, 868, 790, 754, 740, 722, 696, 672, 628, 588,540 and 484 cm⁻¹ ; and its nuclear magnetic resonance spectrum displayedthe olefinic proton at 7.89 ppm in deuterioacetone solution.

Calculated for C₉ H₂ Cl₆ O₂ : C, 30.05; H, 0.57; Cl, 59.95%. Found: C,30.4; H, 0.6; Cl, 60.1%.

EXAMPLE 57 Preparation of α, 2,2,3,3,4,5,6,7-nonachloro-1-indanaceticacid. ##STR71##

When an excess (125 ml) of trichloroethylene was added to the dioxoniumcompound prepared in Example 6 and the resultant mixture was heated at60° C. for a period of 30 minutes, followed by adding it to water,separating and drying the organic phase with anhydrous calcium sulfate,filtrating and stripping under reduced pressure in a rotatingevaporator, there was obtained 42.6 g of an orange oil. Trituration withhexane yielded 22.1 g or 45.5% of the title compound, which afterrecrystallization from benzene, had mp 214-216° C. Its infrared spectrumcontained maxima at and its nuclear magnetic resonance spectrum inhexadeuterioacetone displayed an AB quartet at 5.46 and 6.45 ppm, with J= 11 cps.

Calculated for C₁₁ H₃ Cl₉ O₂ : C, 27.16; H, 0.62; Cl, 65.62%. Found : C,27.7; H, 0.7; Cl, 62.1%.

EXAMPLE 58 Preparation of 1,1,2,2,4,5,6,7-octachloroindan ##STR72##

The oxonium compound of Example 3 was prepared. The excess of sulfurtrioxide was stripped under reduced pressure to a pot temperature of 40°C. at 5 mmHg and the residue was cooled to 10° C. Trichloroethylene (100ml) was added in one portion and after the exothermic reaction was over,the resultant mixture was stirred for 15 minutes, poured onto ice andmost of the solvent was stripped from the organic phase under reducedpressure. Filtration of the thick slurry yielded 39.4 g or aquantitative yield of the title compound, which after recrystallizationfrom benzene had mp 145.5-147.0° C. Its infrared spectrum displayedmaxima in Nujol mull at 1380, 1304, 1242, 1230, 1188, 1120, 968, 932,918, 793, 745, 725, 680, 658, 555, 518 and 480 cm⁻¹ ; and its nuclearmagnetic resonance spectrum showed the benzylic protons as a single peakat 4.38 ppm in DMSO solution and at 3.71 ppm in hexadeuteriobenzenesolution.

Calculated for C₉ H₂ Cl₈ : C, 27.50; H, 0.51; Cl, 72.0%. Found : C,28.1; H, 0.7; Cl, 71.4%.

EXAMPLE 59 Preparation of1,1,2,2,4,5,5,6,6,8-decachloro-1,2,3,5,6,7-hexahydro-s-indacene##STR73##

When the procedure of the preceding example was carried out with thedioxonium compound prepared in Example 18, there was obtained 50.3 g ora quantitative yield of the title compound, mp 175.5-177.0° C., afterrecrystallization from benzene. Its infrared spectrum intetrachloroethylene and carbon disulfide solution contained maxima at1600, 1430, 1374, 1308, 1257, 1180, 1140, 1108, 994, 947, 916, 852, 754,698, 657, 617, 538, 507 and 468 cm⁻¹ and its nuclear magnetic resonancespectrum contained a single peak at 4.48 ppm in hexadeuterioacetonesolution and at 3.77 ppm in hexadeuteriobenzene solution.

Calculated for C₁₂ H₄ Cl₁ O: C, 28.66; H, 0.80; Cl, 70.52% Found : C,29.5; H, 1.0; Cl, 69.3%.

EXAMPLE 60 Preparation of N-pentachlorobenzyl acetamide ##STR74##

When an excess (125 ml) of acetonitrile was added at once to the oxoniumcompound prepared in Example 1, a vigorous reaction ensued, but was keptunder control with strong cooling. After the reaction subsided, themixture was heated to reflux and the light yellow slurry poured intowater. The white powder that precipitated was filtered off and dried inthe air, after which it weighed 36.0 g. Recrystallization from methanolyielded 21.3 g or 66% of the title compound, mp 223.5-224.0° C., whosestructure was established by spectroscopic and elemental analyses. Itsinfrared spectrum from a Nujol mull had maxima at 3270, 1630, 1540,1360, 1320, 1278, 1248, 1232, 1210, 1124, 1040, 1010, 770, 725, 682,632, 592, 510 and 464 cm⁻¹ ; and its nuclear magnetic resonance spectrumin DMSO displayed the benzylic protons at 4.57 ppm, the methyl protonsat 2.53 ppm and the NH proton at 3.32 ppm.

Calculated for C₉ H₆ Cl₅ NO : C, 33.62; H, 1.89; Cl, 55.16%. Found : C,33.7; H, 2.0; Cl, 55.3%.

EXAMPLE 61 Preparation of N-pentachlorobenzyl acrylamide ##STR75##

The procedure of Example 1 was exactly repeated and to the resultantoxonium compound there was added 125 ml of methylene chloride, followedby the addition of 125 ml of acrylonitrile. After the exothermicreaction subsided the resultant light yellow slurry was heated at 60° C.for 0.5 hour. Filtration yielded 12.5 g of solids, shown to be the titlecompound by infrared, nuclear magnetic resonance and elemental analysis.The yield was 37.5%. Recrystallization from methanol yielded crystalswith mp 213-214° C. Its nuclear magnetic resonance spectrum in DMSOconsisted of the vinyl proton multiplets at 6.0-6.4 and 5.5-5.7 ppm, thebenzylic protons at 4.64 ppm and the amide proton at 3.34 ppm.

Calculated for C₁₀ H₆ Cl₅ NO : C, 36.01; H, 1.82; Cl, 53.19% Found : C,36.0; H, 1.8; Cl, 53.1%.

EXAMPLE 62 Preparation of the sodium salt oftrans-2-(pentachlorophenyl)ethene sulfonic acid ##STR76##

When the procedure of Example 1 was repeated with2,3,4,5,6-pentachloroethylbenzene (mp 56-57° C.) replacingpentachlorotoluene and the reaction mixture was refluxed for five hours,stripping of the excess of sulfur trioxide yielded a dark residue whichwas poured into ice water. Neutralization by dilute aqueous sodiumhydroxide and filtration yielded 17.5 g or 43% of theory of the titlecompound as the mono hydrate. Recrystallization from ethanol yielded ananalytical sample, infusible below 300° C. Its nuclear magneticresonance spectrum, run in DMSO, displayed the olefinic protons as an ABquartet at 6.73 and 6.97 ppm, with a coupling constant of 16 cps; theinfrared spectrum, run in FLUOROLUBE and mineral oil mulls, containedmaxima at 3580, 3506, 1610, 1375, 1340, 1304, 1190, 1062, 946, 856, 770,718, 688, 652, 630, 600, 552, 540 and 510 cm⁻¹

Calculated for C₈ H₂ Cl₅ NaO₃ S.H₂ O: C, 24.23; H, 0.51; Cl, 44.72; S,8.09%. Found : C, 24.6; H, 0.9; Cl, 44.5, S, 8.2%.

EXAMPLE 63 Preparation of the sodium salt of pentachlorobenzene sulfonicacid ##STR77##

The procedure of Example 1 was repeated, except that 29.2 g of2,3,4,5,6-pentachlorocumene (mp 78.5-80.0°; bp 106-108° C. at 0.05 mmHg.) was substituted for the toluene. After refluxing for five hours theexcess of sulfur trioxide was distilled off and the dark residue waspoured onto ice, and neutralized with dilute aqueous sodium hydroxidesolution. Filtration of the solids yielded a damp mud which ontrituration with dioxane yielded a white powder, which was found torepresent a 63% yield of the title compound containing one mole water ofcrystallization.

Calculated for C₆ Cl₅ NaO₃ S.H₂ O: C, 19.45; H, 0.55; Cl, 47.86; S,8.65%. Found : C, 19.3; H, 0.7; Cl, 46.6; S, 8.5%.

EXAMPLE 64 Preparation of 2,3,5,6-tetrachloro-p-tolualdehyde ##STR78##

The procedure of Example 9 was repeated except that an excess of 20%fuming sulfuric acid (300 g) was used in place of pure sulfur trioxideand that heating was carried out between 90 and 100° for a period offour hours. During this time a deep purple solution was produced andstrong gas evolution (acidic fumes) accompanied the heating of thereaction mixture. After cooling to room temperature the solution wasadded slowly to ice with good stirring. An orange-yellow precipitateformed which was filtered, washed repeatedly with water and dried in theair, yielding 24.3 g of product. Recrystallization from ethyl acetateand carbon tetrachloride yielded slightly off-white crystals, mp200.0-206.5° C., shown by spectral and elemental analyses to be thetitle compound. Its infrared spectrum in tetrachloroethylene and carbondisulfide solution displayed maxima at 2855, 1720, 1350, 1244, 1230,1140, 1027, 988, 832, 730, 696, 648, 529 and 468 cm⁻¹. Its nuclearmagnetic resonance spectrum in deuteriochloroform consisted of twosinglets: the aldehydic proton at 10.4 ppm and the methyl protons at2.70 ppm in the correct 1:3 area ratio.

Calculated for C₈ H₄ Cl₄ O: C, 37.25; H, 1.56; Cl, 54.98%. Found : C,37.3; H, 1.6; Cl, 54.8%.

EXAMPLE 65 Preparation of 2,3,5,6-tetrachloro-p-tolualdehyde ##STR79##

Repeating the procedure of Example 64 withα,α',2,3,5,6-hexachloro-p-xylene instead of 2,3,5,6-tetrachloro-p-xyleneas the reactant yielded the title compound in 19.6 g or 76% yield.

EXAMPLE 66 Preparation of 2,3,5,6-tetrachloro-p-tolualdehyde ##STR80##

When the procedure of Example 64 was carried by replacingtetrachloro-p-xylene with an equimolar amount (27.6g) of2,3,5,6-tetrachloro-p-xylene-α,α'-diol, a strong evolution of sulfurdioxide was observed (identified qualitatively by iodine paper), but theresultant solution did not turn purple, instead it acquired a brownamber color. After a four hour of heating period between 90 and 94° C.,the clear solution was poured, after it cooled to room temperature, ontoice, yielding a yellow slurry. Since filtration was sluggish, the slurrywas extracted with diethyl ether, yielding, after evaporation of thesolvent 19.0 g of bright yellow solids, whose identity was determined byinfrared and nuclear magnetic resonance spectra, which matched thosedescribed in Example 64.

EXAMPLE 67 Preparation of 3,4,5,6-tetrachloro-o-tolualdehyde ##STR81##

When the procedure of Example 64 was repeated except thattetrachloro-o-xylene was substituted for the para isomer, a 60% yield ofthe title compound, mp 187-194° C., was realized. Its infrared maximaoccurred at 2860, 1705, 1435, 1376, 1348, 1304, 1228, 1170, 1038, 956,894, 660 and 520 cm⁻¹ and its nuclear magnetic resonance spectrum inCDCl₃ displayed the aldehydic proton at 10.50 ppm and the methyl protonsat 2.62 ppm in 1:3 area ratio.

Calculated for C₈ H₄ Cl₄ O: C, 37.25; H, 1.56; Cl, 54.98%. Found: C,37.3; H, 1.6; Cl, 53.6%.

EXAMPLE 68 Preparation of 2,3,4,5,6-pentafluorobenzyl alcohol ##STR82##

Repeating the procedure of Example 23 with the oxonium compound preparedin Example 5 resulted in the formation of a crude product in 14.9 gyield. Gas chromatography of this oil resulted in the isolation of thetitle compound, which was found to constitute 85% of the product, thusgiving a 12.6 g or 63.5% yield. When isolated in pure form, the alcoholin CDCl₃ solution had nuclear magnetic resonance peaks at 4.72 and 3.85ppm in 2:1 ratio, corresponding to the benzylic and hydroxylic protonsrespectively. Its infrared spectrum, run as a Nujol mull, had maxima at3602, 3320, 1498, 1302, 1278, 1216, 1118, 1022, 948, 922, 750, 668, 598,560 and 478 cm⁻¹.

EXAMPLE 69 Preparation of 2,3,5,6-tetrachloro-p-xylene-α,α'-diol##STR83##

When the procedure of Example 25 was repeated without added hydrochloricacid with the dioxonium compound prepared in Example 18 an essentiallyquantitative yield of the title compound was obtained. Quantitativeanalysis of the aqueous phase indicated the presence of four equivalentmoles of sulfuric acid and two equivalent moles of hydrochloric acid, asdemanded by the stoichiometry outlined above.

EXAMPLE 70 Preparation of 2,3,4,5-tetrabromo-6-chlorobenzaldehyde##STR84##

When 2,3,4,5-tetrabromo-6-chlorotoluene, mp 268-269°, was substitutedfor pentabromotoluene in Example 7 and the resultant dioxonium compoundwas hydrolyzed according to the procedure of Example 35 an essentiallyquantitative yield of the title compound was obtained. The structure ofthe novel high melting compound was confirmed by infrared and nuclearmagnetic resonance spectroscopy as well as by elemental analysis.

EXAMPLE 71 Preparation of pentachlorobenzaldehyde ##STR85##

This example illustrates the preparation of pentachlorobenzaldehyde inan oxidation step effected by 20% oleum (fuming sulfuric acid). Whenpentachlorobenzyl chloride, 30.0 g (0.1 mole) was heated gradually andwith good stirring, with 200 g of 20% fuming sulfuric acid, a dark greenslurry was obtained. When the temperature reached 82° C., gas evolution(acidic fumes) began, which became quite copious at 85° C. For thecourse of two hours the color of the slurry changed to brown and afterthree hours of heating between 82° and 85° C. the gas evolutionsubsided. Heating was stopped. After cooling to room temperature thereaction mixture was added to ice, filtered, washed and dried, yieldingthus 24.7 g of a light tan colored product, identified by nuclearmagnetic resonance, infrared and elemental analysis aspentachlorobenzaldehyde, identical with the products described inExamples 33 and 34. The yield accordingly was 88.5% of the theoretical.

What is claimed is:
 1. A process for the preparation of a compound ofthe formula ##STR86## which comprises reacting an excess of neat, liquidsulfur trioxide with a compound of the formula ##STR87## Hal is ahalogen selected from the group consisting of fluorine, chlorine,bromine and iodine;Y is hydrogen or hydroxyl; m is 4 or 5 p is 6-m.
 2. Aprocess according to claim 1 wherein the halogen is chlorine; Y ishydrogen; and m is
 5. 3. A process according to claim 1 wherein thehalogen bromine; Y is hydrogen and m is
 5. 4. A process according toclaim 1 for the preparation of a compound of the formula ##STR88## whichcomprises reacting an excess of neat, liquid sulfur trioxide with acompound of the formula ##STR89##